AlOx surface passivation of black silicon by spatial ALD: Stability under light soaking and damp heat exposure

Ismo T. S. Heikkinen, George Koutsourakis, Sauli Virtanen, Marko Yli-Koski, Sebastian Wood, Ville Vähänissi, Emma Salmi, Fernando A. Castro, Hele Savin

Tutkimustuotos: LehtiartikkeliArticleScientificvertaisarvioitu

41 Lataukset (Pure)

Abstrakti

Scientific breakthroughs in silicon surface passivation have enabled commercial high-efficiency photovoltaic devices making use of the black silicon nanostructure. In this study, the authors report on factors that influence the passivation stability of black silicon realized with industrially viable spatial atomic layer deposited (SALD) aluminum oxide (AlOx) under damp heat exposure and light soaking. Damp heat exposure conditions are 85 °C and 85% relative humidity, and light soaking is performed with 0.6 sun illumination at 75 °C. It is demonstrated that reasonably thick (20 nm) passivation films are required for both black and planar surfaces in order to provide stable surface passivation over a period of 1000 h under both testing conditions. Both surface textures degrade at similar rates with 5 and 2 nm thick films. The degradation mechanism under damp heat exposure is found to be different from that in light soaking. During damp heat exposure, the fixed charge density of AlOx is reduced, which decreases the amount of field-effect passivation. Degradation under light soaking, on the other hand, is likely to be related to interface defects between silicon and the passivating film. Finally, a thin chemically grown SiOx layer at the interface between the AlOx film and the silicon surface is shown to significantly increase the passivation stability under both light soaking and damp heat exposure. The results of this study provide valuable insights into surface passivation degradation mechanisms on nanostructured silicon surfaces and pave the way for the industrial production of highly stable black silicon devices.
AlkuperäiskieliEnglanti
Artikkeli022401
JulkaisuJOURNAL OF VACUUM SCIENCE AND TECHNOLOGY A
Vuosikerta38
Numero2
DOI - pysyväislinkit
TilaJulkaistu - maaliskuuta 2020
OKM-julkaisutyyppiA1 Julkaistu artikkeli, soviteltu

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    Fotoniikan Tutkimus ja Innovaatio

    Savin, H. & Mulbagal Rajanna, P.

    01/01/201931/12/2022

    Projekti: Academy of Finland: Other research funding

    Hybrid metrology for thin films in energy applications

    Savin, H., Modanese, C., Heikkinen, I. & Yli-Koski, M.

    01/06/201731/05/2021

    Projekti: EU: Other research funding

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